Hello, I do not know about how many of you aware of this work of Michael Hines [0], but looks like it can be extremely usable for critical applications using qemu and, of course, Ceph at the block level. My thought was that if qemu rbd driver can provide any kind of metadata interface to mark each atomic write, it can be easily used to check and replay machine states on the acceptor side independently. Since Ceph replication is asynchronous, there is no acceptable approach to tell when it`s time to replay certain memory state on acceptor side, even if we are pushing all writes in synchronous manner. I`d be happy to hear any suggestions on this, because the result probably will be widely adopted by enterprise users whose needs includes state replication and who are bounded to VMWare by now. Of course, I am assuming worst case above, when primary replica shifts during disaster state and there are at least two sites holding primary and non-primary replica sets, with 100% distinction of primary role (>=0.80). Of course there are a lot of points to discuss, like 'fallback' primary affinity and so on, but I`d like to ask first of possibility to implement such mechanism at a driver level. Thanks! 0. http://wiki.qemu.org/Features/MicroCheckpointing -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
